Rehabilitation pipe and pipe rehabilitation method

ABSTRACT

A pipe unit for a rehabilitation pipe is used to rehabilitate an existing pipe. The pipe unit has segments mutually linked in a circumferential direction of the pipe unit, and at least one diameter expander for enlarging an inner diameter of the pipe unit. The diameter expander has a thickness in the circumferential direction of the pipe unit and is inserted between an adjacent pair of the mutually linked segments so as to be completely separated from each other by the diameter expander in the circumferential direction and by an amount corresponding to the thickness of the diameter expander.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rehabilitation pipe for repairing pipeline facilities using segments each comprising an inner surface plate constituting an inner circumferential surface, and side plates and end plates provided upright on peripheral edges of the inner surface plate, wherein the inner surface plate, the side plates, and the end plates are formed integrally from a plastic material and the segments are linked in the circumferential direction and in the pipe-length direction to construct a rehabilitation pipe inside an existing pipe. The present invention also relates to a pipe rehabilitation method using the rehabilitation pipe.

2. Description of the Related Art

In cases in which a sewage pipe or another pipeline buried underground has deteriorated through aging, a pipe lining method has been proposed and practiced in which a lining is provided to the inner circumferential surface thereof to repair the pipeline without excavating it from the ground.

In this pipe lining method, a pipe lining material made of a tubular resin absorbent material impregnated with an uncured thermosetting resin is everted and inserted into a pipeline using fluid pressure, and is pressed by fluid pressure against the inner peripheral wall of the pipeline. The lining material is then heated using a desired method to cure the thermosetting resin therein and form a plastic pipe, thereby repairing the pipeline.

There is also known a lining method using segments each comprising an inner surface plate constituting an inner circumferential surface, side plates and end plates provided upright on the peripheral edges of the inner surface plate, these plates being integrally formed from a plastic material. The segments are linked in the circumferential direction to assemble short pipe units, which are then linked in the pipe-length direction to construct a rehabilitation pipe inside an existing pipe (for example, JP-A 2005-264635). Such a pipe rehabilitation method is used for large-diameter existing pipes. In this method, after assembling a rehabilitation pipe inside the existing pipe, grout or another filler material is injected into a space between the existing pipe and the rehabilitation pipe and hardened to construct a composite pipe.

When a rehabilitation pipe is to be installed in a construction site, there may be instances in which the diameter of the rehabilitation pipe must be made slightly larger than the rated size in order to compensate errors that have arose in constructing the existing pipe or to match other structures. However, a metal mold must be newly manufactured when the size thereof is slightly modified in a method according to JP-A 2005-264635 in which the plastic segments are linked to assemble the rehabilitation pipe. This disadvantageously extends the period of the construction time and increases construction costs.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a rehabilitation pipe and a method for rehabilitating an existing pipe in which the inside diameter of the rehabilitation pipe is made larger than the rated size speedy and cost-effectively.

The present invention provides a rehabilitation pipe for rehabilitating an existing pipe. The rehabilitation pipe comprises a plurality of segments each comprising an inner surface plate, and side plates and end plates provided upright on a peripheral edge of the inner surface plate, the inner surface plate, the side plates, and the end plates being formed integrally from a plastic material. The segments are linked in a circumferential direction to assemble a closed ring-shaped pipe unit and are liked in a pipe-length direction to rehabilitate the existing pipe. A diameter expander is inserted between the segments when they are linked in the circumferential direction to enlarge the diameter of the pipe unit.

The present invention also provides a method for rehabilitating an existing pipe. A plurality of segments is first prepared each comprising an inner surface plate, and side plates and end plates provided upright on a peripheral edge of the inner surface plate, the inner surface plate, the side plates, and the end plates being formed integrally from a plastic material. The segments are linked in a circumferential direction with a diameter expander inserted between the adjacent segments to assemble a closed ring-shaped diameter-enlarged pipe unit. The diameter-enlarged pipe units are sequentially linked in the pipe-length direction to install a segmental rehabilitation pipe inside the existing pipe.

According to the present invention, when the segments are linked in the circumferential direction, a diameter expander in a panel shape is provided between the segments that are adjacent in the circumferential direction, so that the rehabilitation pipe having the inside diameter larger than the rated size can be assembled speedy and cost-effectively.

In the invention, the end plate is provided with an opening for allowing a filler material to flow in or out that is injected into the gap between the rehabilitation pipe and the existing pipe, and the diameter expander is also provided at a position corresponding to the position of the end plate with an opening for allowing the filler material to flow in or out. This allows the filler material injected into the gap to flow in or out in the circumferential direction in a smooth manner and improves the efficiency of the linking operation and the injection operation.

Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and following detailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the structure of a segment used in assembling the rehabilitation pipe;

FIG. 2 a is a front view of a side plate of a segment;

FIG. 2 b is a cross-sectional view along line B-B in FIG. 2 a;

FIG. 2 c is a detailed view of an end plate of the segment viewed from the direction of line A-A in FIG. 2 a;

FIG. 3 a is a front view of an inner plate of the segment;

FIG. 3 b is a cross-sectional view along line C-C in FIG. 3 a;

FIG. 4 is a front view of another inner plate of the segment;

FIG. 5 a is a cross-sectional view showing the segments linked in the circumferential direction with a bolt and a nut using a diameter expander;

FIG. 5 b is a cross-sectional view showing the segments linked in the circumferential direction using a diameter expander;

FIG. 5 c is a front view showing the segments linked in the circumferential direction using a diameter expander;

FIG. 6 is a perspective view showing a state in which the segments are linked in the circumferential direction using a diameter expander to assemble a diameter-expanded pipe unit;

FIG. 7 is a front view showing a state in which the segments are linked in the circumferential direction using a diameter expander to assemble a diameter-expanded pipe unit;

FIG. 8 is an illustrative view showing a state in which the segments of the pipe units are linked in the pipe-length direction using linking members;

FIG. 9 a is a front view of a diameter expander;

FIG. 9 b is a side view of a diameter expander;

FIG. 9 c is a plan view of a diameter expander;

FIG. 10 is an illustrative view showing a state in which the pipe units are linked and the rehabilitation pipe is installed in the existing pipe; and

FIG. 11 is a perspective view showing a state in which the pipe units are linked and the rehabilitation pipe is installed in the existing pipe.

FIG. 12 is a front view showing a state in which the segments are linked in the circumferential direction using a diameter expander to assemble a diameter-expanded pipe unit having a square cross-section;

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described with references to embodiments illustrated in the accompanying drawings. The present invention is suitable for rehabilitating or repairing sewage pipes, water supply pipes, tunnels, agricultural irrigation channels, and other existing large-diameter pipes. In the present embodiment, the rehabilitation pipes are described as having a circular cross-section profile orthogonal to the pipe-length direction. However, it shall be apparent that the present invention can be applied to a rehabilitation pipe having a square or another non-circular cross-section. Also, in addition to structures in which the cross-section profile is closed as a pipe, a structure having a horseshoe-shaped, semi-circular, U-shaped, or another cross-section profile in which one side is open can also be considered to be a pipe, and the present invention can also be applied thereto.

In the present specifications, the pipe-length direction refers to the direction indicated by arrow X extending in the longitudinal direction of a pipe unit 10 in FIG. 6, the radial direction refers to the direction indicated by the radial arrow R pointing towards the center axis of the pipe unit 10, and the circumferential direction refers to the direction of the circumference of the circle forming the pipe unit 10.

FIG. 1 shows the structure of a segment 1 for pipe rehabilitation (hereafter simply referred to as “segment”), which represents an assembly unit member of a rehabilitation pipe for rehabilitating an existing pipe. The segment 1 is an integrally formed block-shaped member made from a plastic material, comprising an inner surface plate 101 constituting an inner circumferential surface of the rehabilitation pipe, side plates 102, 103 provided vertically upright on both sides extending in the circumferential direction of the inner surface plate 101, and end plates 104, 105 provided vertically upright on both ends extending in the pipe-length direction of the inner surface plate 101.

In the present embodiment, the segment 1 has a shape that is curved as an arc representing a predetermined angle that equally divides the circumference, e.g., a 60° arc that divides the circumference into sixths. However, the segment is not limited to that having an arc or a fan shape. The segment may be shaped as, e.g., a cuboid or a shape that is bent so as to have a curved right angle depending on the cross-section profile or the size of the existing pipe or the location of the existing pipe to be repaired.

A plurality (four in the present embodiment) of inner plates 106, 107 having a shape similar to that of the side plates are provided upright at equal intervals and parallel to the side plates 102, 103 on the upper surface of the inner surface plate 101 and on the inside relative to the side plates 102, 103 in order to reinforce the mechanical strength of the segment 1. One or both of the inner plates 106, 107 can be omitted if the segment 1 has sufficient strength.

The inner surface plate 101, the side plates 102, 103, the end plates 104, 105, and the inner plates 106, 107 are all made from an identical transparent, semi-transparent or opaque plastic material, and are integrally formed using a known molding technique.

FIG. 2 a is a detailed view of the side plates 102, 103, and FIG. 2 b is a cross-sectional view along the line B-B in FIG. 2 a. The following descriptions are given in relation to the side plate 102, but the side plate 103 has a configuration similar to that of the side plate 102.

The side plate 102 is an arc-shaped thin-plate member, and an upper section 102 d has a smaller plate thickness than that of a lower section 102 e. This is in order to form a gap on the upper part of the two side plates 102, 103 when one segment is liked to another segment adjacent in the pipe-length direction, and to guide and accommodate earth and other material entering from the exterior.

A plurality of holes 102 a for admitting insertion of a linking member for linking the segment 1 in the pipe-length direction are provided at equal intervals along the circumference on the lower section 102 e of the side plate 102. The holes 102 a in the side plate 102 and holes 103 a in the side plate 103 are located at coinciding positions along the circumferential direction, allowing the linking member to be inserted through the holes 102 a and 103 a in the side plates 102 and 103.

An opening 102 b, used for a linking operation of the segments in the circumferential direction, is provided to the side plate 102 in the vicinity of both ends in the circumferential direction, i.e., at both ends in the vicinity of the end plates 104, 105. Each of the openings 102 b has a rectangular shape in which corners are chamfered. A lower edge of the opening 102 b substantially coincides with a lower edge of the side plate 102, and an upper edge of the opening 102 b is somewhat lower than an upper edge of the side plate 102. When the segments are connected in the circumferential direction, a bolt, a nut, or another linking member is, e.g., positioned or tightened through the opening 102 b (see also FIG. 5 c).

The opening 102 b is configured so that a filler material injected into a space between the existing pipe and the segmental rehabilitation pipe can flow in or out through the opening 102 b, and so that during injection, the filler material can pass through the opening 102 b in a smooth and speedy manner. It is also possible to provide the openings 102 b, 103 b to the vicinity of the end plate 104 only or to the vicinity of the end plate 105 only.

Notches 102 c for allowing the filler material to flow in or out and pass therethrough are provided to an upper section of the side plate 102. The notches 102 c have a half-moon shape in which the upper end is open. The notches 102 c are positioned in the circumferential direction so as to be displaced from the positions of the holes 102 a in the circumferential direction. More specifically, a notch 102 c is provided between the hole 102 a nearest to the end plates 104, 105 and the next hole 102 a, and then provided every two holes 102 a. Thus, a total of seven notches 102 c are provided to the side plate 102.

FIG. 2 c is a detailed view of the end plate 105 as viewed from line A-A in FIG. 2 a. The following descriptions are given in relation to the end plate 105, but the end plate 104 has a configuration similar to that of the end plate 105.

The end plate 105 is a rectangular thin-plate member arranged between the side plate 102 and the side plate 103. The height of the end plate 105 from the outer surface of the inner surface plate 101 is slightly lower than that of the side plates 102, 103. Circular insertion holes 105 a for admitting insertion of a bolt or another linking member for linking the segment 1 in the circumferential direction are provided on the end plate 105 between the side plate 102 and an inner plate 106, between the inner plate 106 and an inner plate 107, between the two inner plates 107, between the inner plate 107 and an inner plate 106, and between the inner plate 106 and the side plate 103.

A concave section 101 a and a convex section 101 b are provided to the inner surface plate 101 along the entire length of the circumferential direction on one end thereof in the pipe-length direction (right end in FIG. 2 c). A convex section 101 c and a concave section 101 d are provided on the other end so that the convex/concave relationship is inverted. As a result, when the segments are linked in the pipe-length direction, the concave and convex sections of segments that are adjacent in the pipe-length direction engage with each other and fulfill the function of guiding or positioning of the segments. This facilitates the operation of linking the segments in the pipe-length direction.

A rectangular opening 105 d for allowing the filler material to flow in or out and pass therethrough is provided to both sides of the inner plates 107, both sides of the inner plates 106, and the inside of the side plates 102, 103 at the lower end of the end plate 105.

A convex section 105 c is provided on the end plate 105 at a position at which it intersects the inner plate 107, and is fitted into a concave section 104 c provided to the corresponding position on the end plate 104 that is adjacent in the circumferential direction (see also FIG. 5 b).

FIG. 3 a is a detailed view of the inner plate 106, and FIG. 3 b is a cross-sectional view along the line C-C in FIG. 3 a. Each of the inner plates 106 is a thin-plate member having a profile substantially identical to the side plates 102, 103. Circular holes 106 a for admitting insertion of linking members for linking the segments in the pipe-length direction are provided at equal intervals to a lower section of the inner plate 106. The positions of the holes 106 a in the circumferential direction coincide with those of the holes 102 a of the side plate 102. As shown in FIG. 3 b, the diameter of each of the holes 106 a increases from the vicinity of the center of the plate thickness of the inner plate 106 towards the outside (i.e., the side towards the side plate).

Notches 106 b for allowing the filler material to flow in or out and pass therethrough are provided to the upper section of the inner plate 106. The notches 106 b have a half-moon shape in which the upper end is open. The positions of the notches 106 b are different in the circumferential direction from those of the holes 102 a, 106 a. More specifically, a notch 106 b is provided further towards the end plate than the hole 106 a nearest to the end plates 104, 105, and are provided every two holes 106 a. Thus, a total of eight notches 106 b are provided. Therefore, the positions of the notches 106 b in the circumferential direction are displaced from those of the notches 102 c of the side plate 102 by an amount equivalent to the intervals between the holes 106 a in the circumferential direction. The notches 106 b and the notches 102 c are thus in a staggered arrangement when the segment is viewed from above. This also applies to the notches 103 c provided to the side plate 103 for passing the filler material, and to the notches 106 b formed on the inner plate 106 adjacent to the side plate 103.

FIG. 4 is a detailed view of the inner plate 107. The inner plate 107 is a thin-plate member having a profile that substantially coincides with the side plates 102, 103. A plurality of notches 107 a is provided from the vicinity of the lower end towards the upper end of the inner plate 107. The positions of the notches 107 a in the circumferential direction coincide at the lower section thereof with those of the holes 102 a in the side plate 102 and the holes 106 a in the inner plate 106. The notch 107 a at the center of the segment 1 is perpendicular to the inner surface plate 101, and the other notches 107 a are oriented so as to be parallel to the notch 107 a in the center. Such an arrangement facilitates removal from the mold when the segment is integrally formed.

FIGS. 5 a, 5 b, and 5 c show a method for linking the segments 1 in the circumferential direction. Two segments 1, 1 are held so that the end plate 105 of one of the segments and the end plate 104 of the other segment are positioned with a diameter expander 120 inserted therebetween. A wrench or another tool, or a technician's finger, is inserted from the opening 102 b in the side plate 102 of the segment, and a bolt 6 is inserted into the insertion holes 104 a, 105 a. A nut 7 is then threadedly engaged to the bolt 6, thereby tightening both end plates 104, 105 and the diameter expander 120 and linking the two segments 1, 1 in the circumferential direction with the diameter expander 120 therebetween. The concave section 104 c and convex section 105 c that fit into the concave section 104 c are formed on the end plate 104 and the end plate 105 at a position at which they intersect with the inner plate 107. As shown in FIG. 9 b, the diameter expander 120 has a convex section 120 c that fits into the concave section 104 c of the end plate 104, and has a concave section 120 b into which the convex section 105 c of the end plate 105 fits (see FIG. 5 b).

A concave section 104 e and a convex section 104 f are formed along the entire length in the pipe-length direction on a lower end of the end plate 104. A convex section 105 f and a concave section 105 e that fit with the concave section 104 e and the convex section 104 f are formed along the entire length in the pipe-length direction on a lower end of the end plate 105. These convexes and concaves are configured so as to fit concaves 120 e and 120 h and convexes 120 f and 120 g that are formed at the lower end of the diameter expander 120 (see FIG. 9 b). Such an arrangement facilitates the task of positioning the two segments 1 and bringing the two segments in close contact with the diameter expander 120 when the segments are linked in the circumferential direction. Also, applying a sealing material (not shown) to the fitting section makes it possible to enhance the water-tightness of the linking section. Bolting as described above is performed in two locations, i.e., between the side plate 102 and the adjacent inner plate 106, and between the side plate 103 and the adjacent inner plate 106. In an instance in which the linking in two locations as described above results in insufficient linking strength, a linking member is also positioned in other insertion holes 104 a, 105 a, 120 a from above the segment, between the inner plates 106, 107 to strengthen the linking in the circumferential direction.

In FIG. 5 a, one bolt/nut set is used per location. However, in an instance in which the end plates 104, 105 have a large height because of segments used for large-diameter existing pipes, the segments can be linked in the circumferential direction using two or more bolt/nut sets per location.

The segments are thus linked in the circumferential direction through the openings 102 b, 103 b provided to the side plates 102, 103. When the segments are linked in the pipe-length direction so that the opening 102 b of the segment is in alignment with the opening 103 b of the adjacent segment and both the segments come in close contact with each other, each set of the openings 102 b, 103 b forms a single integral opening. Therefore, when the filler material is injected into the spacing between the existing pipe and the rehabilitation pipe after installation of the rehabilitation pipe, the filler flows in or out through the integrated openings 102 b, 103 b without flowing downwards towards the interior of the rehabilitation pipe. Therefore, there is no need to block the openings 102 b, 103 b, and linking in the circumferential direction can be performed in a simpler manner compared to an instance in which an opening is provided to the inner surface plate 101.

By sequentially linking the segments 1 in the circumferential direction around the full circumference, it is possible to assemble a closed ring-shaped short pipe assembly 10 (hereafter referred to as “pipe unit”) having a predetermined small length in the pipe-length direction X as shown in FIG. 6. The pipe unit 10 has a shape that can be obtained when a circular pipe is sliced at a predetermined width D perpendicularly to the pipe-length direction X. The outside diameter of the pipe unit 10 is slightly smaller than the inside diameter of the existing pipe to be rehabilitated. The segment 1 corresponds to a member obtained by dividing the pipe unit 10 into a plurality of (preferably equal) portions along a cutting surface parallel to the radial direction R.

The diameter expander 120 is inserted between the segments 1, so that the inside diameter of the pipe unit 10 is enlarged by an amount of thickness of the expander 120. For example, assuming that the thickness of the diameter expander 120 be 8 mm, the inside diameter of the pipe unit 10 is made 8×6/π=15 mm larger than without the diameter expander. In FIG. 6, the diameter expanders 120 are used at all the liking locations in the circumferential direction, but it may be acceptable that they are used only at some locations.

In FIG. 6, the inner surface plate 101, the side plates 102, 103, and the end plates 104, 105, which are the principal structural members of the segment 1, are shown. In order to prevent the drawing from becoming complicated, the inner plates 106, 107 and other reinforcement structures are not shown.

FIG. 7 is a front view showing a state in which the segments are linked in the circumferential direction using a diameter expander to assemble a diameter-expanded pipe unit. The pipe unit is substantially circular in cross-section and slightly bent at locations at which the diameter expanders 120 are inserted, but no practical problems arise because the diameter expander 120 is sufficiently smaller in length in the circumferential direction than the segments 1.

Each of the segments in the pipe unit 10 of such description is linked to a segment of another pipe unit using a linking member (tightening member) 11 and a nut 12 as shown in FIG. 8 for extension in the pipe-length direction.

The nut 12 is passed through a hole 102 a in the side plate 102 of one segment 1 a and brought into contact with the first inner plate 106, i.e., the inner plate 106 positioned nearest to the side plate 102. A bolt 13 is threaded into the nut 12, and the nut 12 is tightened against the inner plate 106 and fixed against it.

The length of the nut 12 in the pipe-length direction is slightly greater than the spacing between the side plate 102 and the inner plate 106, and is such that the nut 12 protrudes outwards from the side plate 102 of the segment 1 a when positioned as above. The amount of protrusion is equivalent to or greater than the thickness of the side plate 103 of the other segment 1 b. Therefore, the nut 12 is passed through the hole 103 a in the side plate 103 of the other segment 1 b, and the two segments 1 a, 1 b are placed against each other.

In this state, a linking member 11 is passed through a hole 102 a in the side plate 102, a hole 106 a in the inner plate 106, and a notch 107 a in the inner plate 107 of the segment 1 b, and a threaded section 11 b of the linking member 11 is threaded into the nut 12 to link the linking member 11 and the nut 12. The linking member 11 is further threaded into the nut 12 until a flange section 14 a of a head section 14 presses against the leftmost inner plate 106 of the segment 1 b to tighten and fix the two segments 1 a, 1 b.

A plurality of the nuts 12 are fixed along the circumferential direction to each segment, the nuts 12 being fixed to every second hole 102 a, or at less regular intervals, depending on the required strength. The segments are linked in the pipe-length direction with the nut positions in each segment being displaced in the circumferential direction relative to the nut positions in the segment adjacent to the segment in question. For example, in the example shown in FIG. 8, the positions of the nuts 12 in the segment 1 a in the center is displaced relative to the positions of the nuts 12 in the segment 1 c adjacent to the right side of the segment 1 a by an amount corresponding to the intervals between the holes 102 a in the side plate 102 as viewed in the circumferential direction.

Thus, the segments of the pipe unit are linked in the pipe-length direction to the segments of another pipe unit, whereby it is possible to link the pipe units in the pipe-length direction to a desired length, and to create a rehabilitation pipe comprising the pipe units or the segments.

FIGS. 9 a-9 c are front, side and plan views of the diameter expander 120. The diameter expander 120 is made from the same plastic material as the segment 1, and is formed similarly thereto using a known molding technique.

The diameter expander 120 has a height indicated by h in FIG. 9 a, and is sufficiently smaller in thickness b than the circumferential length of the pipe unit 10.

The diameter expander 120 is provided at its upper portion with protrusions 122, 126, 127 and 123, whose position respectively coincides with that of the side plate 102, the inner plates 106, 107, and the side plate 103 in the pipe-length direction, and whose thickness is the same as that of the side plate 102, the inner plates 106, 107, and the side plate 103, respectively (also see FIG. 8).

The diameter expander 120 is also provided at its upper portion with five circular insertion holes 120 a and at its lower portion with ten rectangular openings 120 d. The diameter expander 120 is set between two segments so that the positions of the holes 120 a respectively coincide with those of the holes 104 a, 105 a of the end plates 104, 105, and the positions of the openings 120 d with those of the openings 104 d, 105 d.

The diameter expander 120 has two concave sections 120 b formed at the position of the protrusion 127 and at a surface at which the end plate 105 contacts therewith when the diameter expander 120 is set, and also has two convex sections 120 c at a surface at which the end plate 104 contacts. The diameter expander 120 also has a concave section 120 e and a convex section 120 f at its lower portion and at a surface at which the end plate 105 contacts therewith when the diameter expander 120 is set, and has a convex section 120 g and a concave section 120 h at a surface at which the end plate 104 contacts. The concave and convex sections of the diameter expander 120 are configured so as to be similar to those of the concave and convex sections of the end plates 104, 105 (also see FIG. 5).

A description will now be given for a method for rehabilitating an existing pipe using the segments configured as described above.

First, as shown in FIG. 10, the segment 1 is carried through a manhole 20 into an existing pipe 21, and as shown in FIGS. 5 and 6, the segments 1 are sequentially linked in the circumferential direction to assemble the diameter-enlarged pipe unit 10.

Next, the pipe units 10 are sequentially linked in the pipe-length direction via the linking members 11 using the method shown in FIG. 8, and as shown in FIGS. 10 and 11, the diameter-enlarged rehabilitation pipe 40 is installed in the existing pipe 21. In FIGS. 10 and 11, the linking members 11 and similar elements are not shown, and the segments are shown in a simplified manner.

If the diameter of the rehabilitation pipe is large, the segments 1 that have been carried in can be transported to the location of actual installation, and the segments are linked in the circumferential direction and the pipe-length direction at this location. In such an instance, there may be instances in which the gap between the outside of the segments and the existing pipe is narrow when linking the segments in the circumferential direction. This may obstruct the mounting of bolt-and-nut sets from the outside of the segment; the benefit of providing the side plates with openings for linking the segments in the circumferential direction is particularly high.

Next, as shown in FIG. 11, a grout material or another filler material 30 is injected into a space S between the rehabilitation pipe 40 and the existing pipe 21, and the filler material is hardened. Both end sections of the space S are blocked using a resin pate, mortar, or another sealing agent. For injection of the filler material, an injection hole is formed in, e.g., the inner surface plate 101, and the filler material 30 is injected therefrom. Injection is performed until the filler material 30 has reached the entirety of the rehabilitation pipe and has started to flow out from the side plates of segments on both ends in the pipe-length direction. During injection, the filler material 30 don't flow out from the openings 102 b, 103 b of the side plates 102, 103 into the inside of the rehabilitation pipe 40. Such openings, therefore, improve the efficiency of the linking operation and the injection operation.

Since the notches 102 c, 103 c, 106 b are respectively provided to the side plates 102, 103 and the inner plate 106 of the segment 1, the filler material can flow smoothly in the pipe-length direction even if the space S is small or if an obstacle is present in the space S. Also, since the notches 102 c, 103 c formed in the side plate 102 or 103 and the notches 106 b formed in the adjacent inner plate 106 are staggered when the segment is viewed from above (outside), the filler material is injected in a zigzag shape, thus allowing the filler material to be injected in a uniform manner.

The height of the end plates 104, 105 and the diameter expander 120 is smaller than the height of the side plates 102, 103 and the inner plates 106, 107, as shown in FIG. 5 c, and there is a significant gap between the upper end of the end plates 104, 105 and the existing pipe 21; therefore, the filler material can also flow smoothly in the circumferential direction.

The openings 104 d, 105 d, 120 d provided to the lower section of the end plates 104, 105 and the diameter expander 120 not only allow the filler material to flow in or flow out and pass through because they are all in alignment, but also function as a passage for air between the existing pipe 21 and the inner surface plate 101 pushed out when injecting the filler material, therefore allowing the filler material to flow in an even smoother manner.

The injected filler material 30 allows the existing pipe 21 and the diameter-enlarged rehabilitation pipe 40 to be solidly bound when it is hardened, and it becomes possible to create a composite pipe comprising the existing pipe, the filler material, and the rehabilitation pipe.

Next, another embodiment will be described in which the invention is applied to a pipeline of a square cross-section. FIG. 12 is a front view showing a state in which the segments are linked in the circumferential direction using a diameter expander to assemble a diameter-expanded pipe unit 20 of a square cross-section. The pipe unit 20 comprises four L-shaped segments 2 and four straight segments 3. Eight diameter expanders 130 are inserted between the segments 2, 3 to make the diameter of the pipe unit 20 larger than without the diameter expander 130. In this embodiment, the segments 2, 3 are linked via the diameter expanders 130 straightforwardly in the circumferential direction, so that no distortion arises in a cross-sectional shape. Therefore, a ratio of the thickness of the diameter expander to the circumferential length is made larger than in the first embodiment.

The segments 2, 3 have a structure similar to that of the segment 1 and is made from the same material as the segment 1, so that detailed explanation will be omitted. The diameter expander 130 corresponds in shape to the end plates of the segments 2, 3, as is the case with the diameter expander 120 as shown in FIGS. 9 a-9 c. 

What is claimed is:
 1. A rehabilitation pipe for rehabilitating an existing pipe, the rehabilitation pipe comprising: a plurality of segments each comprising an inner surface plate, and side plates and end plates provided upright on a peripheral edge of the inner surface plate, the inner surface plate, the side plates and the end plates being formed integrally from a plastic material, and the segments being linked in a circumferential direction to assemble a closed ring-shaped pipe unit and being linked in a pipe-length direction to form the rehabilitation pipe for rehabilitating the existing pipe; and a diameter expander inserted between an adjacent pair of the linked segments for enlarging an inner diameter of the pipe unit, the diameter expander having a thickness extending in the circumferential direction of the linked segments so as to enlarge the inner diameter of the pipe unit by an amount corresponding to the thickness of the diameter expander, wherein the end plate of each segment of the adjacent pair of linked segments is provided with a concave section and a convex section, and the diameter expander is provided with a convex section and a concave section configured to fit into the concave section and the convex section, respectively, of the end plate.
 2. A rehabilitation pipe according to claim 1, wherein the end plate of each segment of the adjacent pair of the linked segments is provided with an opening for allowing a filler material that is injected into a gap between the rehabilitation pipe and the existing pipe to flow therethrough, and the diameter expander is provided with an opening at a position corresponding to the position of the opening of the end plate for allowing the filler material to flow in or out therethrough.
 3. A rehabilitation pipe according to claim 1, wherein the end plate of each segment of the adjacent pair of the linked segments is provided with an insertion hole for admitting insertion therethrough of a linking member for linking the segments in the circumferential direction, and the diameter expander is provided with an insertion hole at a position corresponding to the position of the insertion hole of the end plate for admitting insertion therethrough of the linking member.
 4. A rehabilitation pipe according to claim 1, wherein the adjacent pair of the linked segments are linked by a linking member that tightens the end plates of the adjacent pair of the linked segments with the diameter expander inserted therebetween so that the end plates are separated from each other in the circumferential direction by an amount corresponding to the thickness of the diameter expander.
 5. A rehabilitation pipe according to claim 4, wherein the end plates are completely separated from each other by the diameter expander so that the end plates are not in direct contact with one another.
 6. A rehabilitation pipe according to claim 1, wherein the diameter expander is inserted between the end plates of the adjacent pair of the linked segments so as to extend at least along an entire upright extension of the end plates from the peripheral edge of the corresponding inner surface plate.
 7. A rehabilitation pipe according to claim 1, wherein the diameter expander comprises a plurality of diameter expanders inserted between a respective plurality of adjacent pairs of the linked segments for enlarging the inner diameter of the pipe unit.
 8. A method for rehabilitating an existing pipe, comprising: preparing a plurality of segments each comprising an inner surface plate, and side plates and end plates provided upright on a peripheral edge of the inner surface plate, the inner surface plate, the side plates and the end plates being formed integrally from a plastic material; linking the plurality of segments to form a plurality of closed ring-shaped pipe units, each of the pipe units being formed by linking the segments in a circumferential direction together with a diameter expander inserted between the end plates of an adjacent pair of the linked segments to assemble the pipe unit, the end plates of the adjacent pair of linked segments being separated from each other by an amount corresponding to a thickness of the diameter expander that extends in the circumferential direction of the linked segments so as to enlarge an inner diameter of the pipe unit by the amount corresponding to the thickness of the diameter expander, wherein each of the end plates of the adjacent pair of linked segments is provided with a concave section and a convex section, and the diameter expander is provided with a convex section and a concave section configured to fit into the concave section and the convex section, respectively, of the end plate; and sequentially linking the pipe units in a pipe-length direction of the existing pipe to form a segmental rehabilitation pipe inside the existing pipe for rehabilitating the existing pipe.
 9. A method for rehabilitating an existing pipe according to claim 8, wherein each of the end plates of the adjacent pair of the linked segments is provided with an opening for allowing a filler material that is injected into a gap between the rehabilitation pipe and the existing pipe to flow therethrough, and the diameter expander is provided with an opening at a position corresponding to the position of the opening of the end plate for allowing the filler material to flow therethrough.
 10. A method for rehabilitating an existing pipe according to claim 8, wherein each of the end plates of the adjacent pair of the linked segments is provided with an insertion hole for admitting insertion therethrough of a linking member for linking the segments in the circumferential direction, and the diameter expander is provided with an insertion hole at a position corresponding to the position of the insertion hole of the end plate for admitting insertion therethrough of the linking member.
 11. A method for rehabilitating an existing pipe according to claim 8, wherein the linking of the segments to form each of the pipe units further comprises tightening with a linking member the end plates of each of the adjacent pair of the linked segments with the diameter expander inserted therebetween so that the end plates are separated from each other in the circumferential direction by the amount corresponding to the thickness of the diameter expander.
 12. A method for rehabilitating an existing pipe according to claim 11, wherein the end plates are completely separated from each other by the diameter expander so that the end plates are not in direct contact with one another.
 13. A method for rehabilitating an existing pipe according to claim 8, wherein the diameter expander is inserted between the end plates of the adjacent pair of the linked segments so as to extend at least along an entire upright extension of the end plates from the peripheral edge of the corresponding inner surface plate.
 14. A method for rehabilitating an existing pipe according to claim 8, wherein the diameter expander comprises a plurality of diameter expanders, and wherein each of the pipe units is formed by linking the segments so that the plurality of diameter expanders are inserted between the end plates of a respective plurality of adjacent pairs of the linked segments to enlarge the inner diameter of the pipe unit. 